I am designing a low voltage installation and the customer asked for a cell for a load bank. Now he drew this in 4-phase, but I did not encounter this before. Is this possible? I thought they were always 3-phase.

\$\begingroup\$@JSO: Be careful with "bad habit of calling it 4-phase." It means that you are missing something fundamental in your understanding. With proper understanding the two would be so different that you couldn't confuse them.\$\endgroup\$
– TransistorMar 25 at 10:01